Topic Contents

Catecholamines in Blood

Test Overview

A test for catecholamines measures the
amount of the
hormones epinephrine, norepinephrine, and dopamine
in the blood. These catecholamines are made by
nerve tissue, the brain, and the
adrenal glands. Catecholamines help the body respond
to stress or fright and prepare the body for "fight-or-flight"
reactions.

The
adrenal glands make large amounts of catecholamines as a reaction to stress. The
main catecholamines are epinephrine (adrenaline), norepinephrine
(noradrenaline), and dopamine. They break down into vanillylmandelic acid (VMA),
metanephrine, and normetanephrine. Metanephrine and normetanephrine also may be measured during a catecholamine test.

Catecholamines increase heart rate, blood
pressure, breathing rate, muscle strength, and mental alertness. They also
lower the amount of blood going to the skin and intestines and increase blood going to the
major organs, such as the brain, heart, and kidneys.

Certain rare
tumors (such as a
pheochromocytoma) can increase the amount of
catecholamines in the blood. This causes high blood pressure, excessive
sweating, headaches, fast heartbeats (palpitations), and tremors.

Why It Is Done

A catecholamine test is done to help
diagnose a tumor in the adrenal glands called a pheochromocytoma. Catecholamine
levels in the blood can change quickly, so it may be hard to find high values
in a single blood sample. But a special compound, metanephrine, may be found in
the blood, which may mean a pheochromocytoma is present. Doctors may want to do
a urine test that measures catecholamine levels over 24 hours.

How To Prepare

You may be asked to avoid the following
foods and fluids for 2 to 3 days before having this test:

Caffeine, such as coffee, tea, cocoa, and
chocolate

Amines. These are found in bananas, walnuts, avocados,
fava beans, cheese, beer, and red wine.

Any foods or fluids with
vanilla

Licorice

Aspirin

You may be asked to not eat or drink anything for 10 hours
before this test. Do not use tobacco for 4 hours before the blood test.

Many medicines may change the results of this test. Be sure to tell your
doctor about all the
nonprescription and prescription medicines you
take.

Your doctor may ask you to stop certain medicines, such as
blood pressure medicines, before the test. Do not take cold or allergy
remedies, including aspirin, or nonprescription diet pills for 2 weeks before
the test.

Having a blood sample taken can cause stress. This may
increase catecholamine levels. Be sure to keep warm, because being cold can
also increase your catecholamine levels. Ask for a blanket if you feel
cold.

Talk to your doctor about any concerns you have regarding
the need for the test, its risks, how it will be done, or what the results will
mean. To help you understand the importance of this test, fill out the
medical test information form(What is a PDF document?).

How It Is Done

The health professional drawing your
blood will:

Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.

Clean the needle site with
alcohol.

Put the needle into the vein. More than one needle stick
may be needed.

Attach a tube to the needle to fill it with
blood.

Remove the band from your arm when enough blood is
collected.

Put a gauze pad or cotton ball over the needle site as
the needle is removed.

Put pressure on the site and then put on a
bandage.

How It Feels

The blood sample is taken from a vein in
your arm. An elastic band is wrapped around your upper arm. It may feel tight.
You may feel nothing at all from the needle, or you may feel a quick sting or
pinch.

Risks

There is very little chance of a problem from
having a blood sample taken from a vein.

You may get a small bruise at the site. You can
lower the chance of bruising by keeping pressure on the site for several
minutes.

In rare cases, the vein may become swollen after the blood
sample is taken. This problem is called phlebitis. A warm compress can be used
several times a day to treat this.

Results

A test for catecholamines measures the
amount of epinephrine, norepinephrine, and dopamine in the blood. These
catecholamines are made by
nerve tissue, the brain, and the
adrenal glands. The test also may measure the amounts of metanephrine and normetanephrine.

Normal

The normal values listed here—called a reference range—are just a guide. These ranges vary from lab to lab, and your lab may have a different range for what's normal. Your lab report should contain the range your lab uses. Also, your doctor will evaluate your results based on your health and other factors. This means that a value that falls outside the normal values listed here may still be normal for you or your lab.

What To Think About

This test is not done very often. The 24-hour
urine test is better for finding high levels of catecholamines than a blood
test. To learn more about a catecholamine urine test, see the topic
Catecholamines in Urine.

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